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package facebook;

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.servlet.DispatcherType;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 *
 * @author Antonio
 */
@WebFilter(filterName = "OAuthFilter", urlPatterns = {"/fbapp/OAuthFilter"}, 
        dispatcherTypes = {DispatcherType.ERROR, DispatcherType.REQUEST})
public class OAuthFilter implements Filter {

    private static final boolean debug = false;
    // The filter configuration object we are associated with.  If
    // this value is null, this filter instance is not currently
    // configured. 
    private FilterConfig filterConfig = null;
    private final String fbOAuthURL = "https://www.facebook.com/dialog/oauth?",
            fbAccessTokenURL = "https://graph.facebook.com/oauth/access_token?",
            clientID = "221957824499054",
            scope = "user_events,friends_events,user_location,"
            + "offline_access";

    public OAuthFilter() {
    }

    private void doBeforeProcessing(ServletRequest request, ServletResponse response)
            throws IOException, ServletException {
        if (debug) {
            log("FacebookOauthFilter:DoBeforeProcessing");
        }

        // Write code here to process the request and/or response before
        // the rest of the filter chain is invoked.

        // For example, a logging filter might log items on the request object,
        // such as the parameters.
        /*
        for (Enumeration en = request.getParameterNames(); en.hasMoreElements();) {
            String name = (String) en.nextElement();
            String values[] = request.getParameterValues(name);
            int n = values.length;
            StringBuffer buf = new StringBuffer();
            buf.append(name);
            buf.append("=");
            for (int i = 0; i < n; i++) {
                buf.append(values[i]);
                if (i < n - 1) {
                    buf.append(",");
                }
            }
            log(buf.toString());
        }
        */
    }

    private void doAfterProcessing(ServletRequest request, ServletResponse response)
            throws IOException, ServletException {
        if (debug) {
            log("FacebookOauthFilter:DoAfterProcessing");
        }

        // Write code here to process the request and/or response after
        // the rest of the filter chain is invoked.

    }

    /**
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    @Override
    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain)
            throws IOException, ServletException {

        if (debug) {
            log("FacebookOauthFilter:doFilter()");
        }


        doBeforeProcessing(req, res);

        //casting request and response
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String redirectURI = Utilities.getBaseUrl(request) + "/fbapp/OAuthFilter";
            String fbAppURI = "http://apps.facebook.com/delo-project/";
            HttpSession session = request.getSession();
            String code = request.getParameter("code");
            if (code == null) {
                String code_req = fbOAuthURL + "client_id=" + clientID
                        + "&redirect_uri=" + redirectURI + "&scope=" + scope + "&state="
                        + session.getAttribute("state");
                response.sendRedirect(code_req);
            }

            if (session.getAttribute("state").equals(request.getParameter("state"))) {

                String access_token_req = fbAccessTokenURL + "client_id=" + clientID
                        + "&redirect_uri=" + redirectURI + "&client_secret="
                        + Utilities.getClientSecret() + "&code=" + code;

                if (request.getParameter("error") != null) {
                    out.println("There has been an error for the following reason: "
                            + request.getParameter("error_description"));
                } else {
                    //exceptions not treated
                    //String oauth_token = Utilities.getAccessToken(access_token_req);
                    //store the token in DB or set cookie
                    response.sendRedirect(fbAppURI);
                }
            } else {
                out.println("The state does not match. You may be a victim of CSRF.<br>");
            }
        } catch (NullPointerException npe) { //if this servlet is called directly
            response.sendRedirect(Utilities.getBaseUrl(request));
        } catch (Exception e) {
            out.println("Some not treated exception: " + e.toString() + "<br>");
        } finally {
            out.close();
        }


        Throwable problem = null;
        try {
            chain.doFilter(request, response);
        } catch (Throwable t) {
            // If an exception is thrown somewhere down the filter chain,
            // we still want to execute our after processing, and then
            // rethrow the problem after that.
            problem = t;
        }

        doAfterProcessing(request, response);

        // If there was a problem, we want to rethrow it if it is
        // a known type, otherwise log it.
        if (problem != null) {
            if (problem instanceof ServletException) {
                throw (ServletException) problem;
            }
            if (problem instanceof IOException) {
                throw (IOException) problem;
            }
            sendProcessingError(problem, response);
        }
    }

    /**
     * Return the filter configuration object for this filter.
     */
    public FilterConfig getFilterConfig() {
        return (this.filterConfig);
    }

    /**
     * Set the filter configuration object for this filter.
     *
     * @param filterConfig The filter configuration object
     */
    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }

    /**
     * Destroy method for this filter 
     */
    @Override
    public void destroy() {
    }

    /**
     * Init method for this filter 
     */
    @Override
    public void init(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
        if (filterConfig != null) {
            if (debug) {
                log("FacebookOauthFilter:Initializing filter");
            }
        }
    }

    /**
     * Return a String representation of this object.
     */
    @Override
    public String toString() {
        if (filterConfig == null) {
            return ("FacebookOauthFilter()");
        }
        StringBuilder sb = new StringBuilder("FacebookOauthFilter(");
        sb.append(filterConfig);
        sb.append(")");
        return (sb.toString());
    }

    private void sendProcessingError(Throwable t, ServletResponse response) {
        String stackTrace = getStackTrace(t);

        if (stackTrace != null && !stackTrace.equals("")) {
            try {
                response.setContentType("text/html");
                PrintStream ps = new PrintStream(response.getOutputStream());
                PrintWriter pw = new PrintWriter(ps);
                pw.print("<html>\n<head>\n<title>Error</title>\n</head>\n<body>\n"); //NOI18N

                // PENDING! Localize this for next official release
                pw.print("<h1>The resource did not process correctly</h1>\n<pre>\n");
                pw.print(stackTrace);
                pw.print("</pre></body>\n</html>"); //NOI18N
                pw.close();
                ps.close();
                response.getOutputStream().close();
            } catch (Exception ex) {
            }
        } else {
            try {
                PrintStream ps = new PrintStream(response.getOutputStream());
                t.printStackTrace(ps);
                ps.close();
                response.getOutputStream().close();
            } catch (Exception ex) {
            }
        }
    }

    public static String getStackTrace(Throwable t) {
        String stackTrace = null;
        try {
            StringWriter sw = new StringWriter();
            PrintWriter pw = new PrintWriter(sw);
            t.printStackTrace(pw);
            pw.close();
            sw.close();
            stackTrace = sw.getBuffer().toString();
        } catch (Exception ex) {
        }
        return stackTrace;
    }

    public void log(String msg) {
        filterConfig.getServletContext().log(msg);
    }
}
